Area Forecast Discussion
Issued by NWS Sterling, VA

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992 FXUS61 KLWX 201842 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 242 PM EDT Mon Mar 20 2017 .SYNOPSIS... A weak cold front will cross the region tonight. A stronger cold front will cross the area Tuesday night. High pressure will return Wednesday through Thursday night. A warm front will cross the region Friday. Low pressure may affect the area Sunday. && .NEAR TERM /THROUGH TONIGHT/... A high pressure ridge resides atop the area this afternoon. However, mid and high clouds have been streaming across the area, due to both warm advection as well as residual blowoff from midwest convection earlier this morning. These clouds are the thickest across the Baltimore-Washington area, although they will be thickening areawide before sunset. Recent runs of the HRRR and RAP both suggest that precipitation won`t be arriving until late this evening, and when it does it`ll be sliding across central Virginia. Have lowered PoPs, but still have at least likelies in the late evening-early overnight hours...highest in the southwest. Will be tapering precipitation off pre-dawn. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Area will be in northwest flow on Tuesday. The downsloping will keep it dry, although its looking quite cloudy (we will be in the baroclinic zone). A stronger cold front will cross late Tuesday night. The thermal packing will be aloft (clearly evident at 850 mb), so anticipate the front will be marked more by a surge of wind. Precipitation continues to be pressed south; have trimmed PoPs once again. There still will be a chase between exiting moisture and approaching cold air, but with PoPs very low, this should be a non-factor. Wednesday and Wednesday night will largely be marked by cold advection. This will be the coldest part of the upcoming week. Entire area easily will be in the 20s by late Wednesday night. && .LONG TERM /THURSDAY THROUGH SUNDAY/... An area of high pressure will be overhead Thursday and Thursday night. Dry air and chilly temperatures are expected across the region. This high pressure will move to the coast Friday and Friday night to allow for a return flow and milder air to develop for the mid- Atlantic. A cold front will sag across the Eastern Great Lakes Saturday before stalling across our region Saturday night. A chance for rain showers will develop during this period. A storm system will develop along the west end of this stalled front on Sunday, keeping the chance for rain showers in the region. The storm system will move east along the front toward the East Coast. The chance for rain showers linger throughout Sunday night. More rain showers could develop along an associated cold front that should also stall across our region on Monday. Temperatures will be more seasonable. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... VFR this afternoon and evening. Clouds will be thickening though, as showers approach. The core of this precip looks like it`ll be sliding south of the terminals though, so am more optimistic with regard to flight restrictions. There may still be a period of MVFR overnight. Low clouds will be persistent Tuesday. Believe ceilings will be low-end VFR. Higher based MVFR certainly within reason. A secondary cold front will be crossing Tuesday night, before the Wednesday morning push. Gusts to 25 kt will mark the frontal passage. VFR/northwest flow on Wednesday, with decreasing winds through the end of the week. && .MARINE... Light winds through midday Tuesday. The direction will be variable through Tuesday morning, with northwest flow then prevailing. Anticipate a surge late Tuesday night. Small Craft criteria will be met. The only question will be when: late Tuesday night vs Wednesday morning. Winds will be decreasing Thursday and Friday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...HTS NEAR TERM...HTS SHORT TERM...HTS LONG TERM...KLW AVIATION...HTS MARINE...HTS

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